The Post has learned point guard Chris Smith, J.R. Smith’s brother who injured his knee during Knicks training camp, has fired his agent, Marc Cornstein, and will hire J.R.’s rep, CAA superagent Leon Rose, who also handles Carmelo Anthony.

J.R. Smith is expected to opt out of his contract and re-sign with the Knicks in a four-year deal starting at about $5 million because the Knicks own his early-Bird rights rules.

The Knicks could be outbid for J.R. Smith by an under-the-cap team, though it’s unlikely considering his playoff flop. But having Chris Smith as part of the package has convinced the Sixth Man of the Year he wants to stay. After the Game 6 loss Saturday, the embattled Smith said “I want to retire a Knick.’’

His brother, Chris, who played at Louisville, tweeted yesterday: “Will be back next season along with my big brother @TheRealJRSmith.’’

*GM Glen Grunwald tried to get Prigioni to sign for two years, but he opted for the one year at the league minimum of $473,000, thinking he could get a larger wage in his second season once he proved himself. The Knicks are in a tough spot because even if they make him a qualifying offer of $900,000, they ultimately would need to use part of their $3 million mini mid-level exception to re-sign him.

* Amar’e Stoudemire on the disappointing season: “It’s never easy when you fall short of a championship. It’s never easy when you have high expectations. Definitely me conquering injuries was the story of the season, but we still had a chance to do something special.”

* Carmelo Anthony shot a combined 2-of-14 for six points in the fourth quarter of the three games in Indiana — all losses. Anthony led the Knicks in scoring in all six games. The Pacers had each of the five starters lead the team in scoring at least once. … The Knicks’ bench outscored Pacers 187-89.